A number of diagnostic and therapeutic vascular procedures are now performed transluminally, where a catheter is introduced through an introducer sheath to the vascular system at a convenient access site and guided through the vascular system to a target location. Such intravascular procedures, include angiographic dye injection, cardiac catheterizations, balloon angioplasty, stent therapy and other types of recanalizing of atherosclerotic arteries and veins.
In these intravascular procedures, an instrument, such as an angiographic needle, is inserted percutaneously through the skin into an artery, such as the femoral artery. A guide wire is then passed through the cannula of the instrument into the artery to the desired depth. Once the guide wire is inserted, the needle cannula is removed, leaving the guidewire in place. An introducer sheath and an arterial dilator or catheter are then passed over the guidewire, through the puncture or incision and into the artery. The guidewire and then the dilator are each removed leaving the introducer sheath or catheter in place. A catheter, or other intravascular instrument, is then inserted through the introducer sheath and threaded down the artery to the desired intravascular location. Because such catheter-based medical procedures require direct vascular access with a vascular puncture, the vascular access site must be closed when the procedure is completed.
When vascular access is no longer required, the introducer sheath is removed and hemostasis is attempted. One common approach is to apply an external force at the puncture site, typically by manual or digital compression. This approach suffers from a number of disadvantages. It is time-consuming, frequently requiring up to one-half hour or more of compression before hemostasis is assured. This procedure is uncomfortable for the patient and frequently requires administering analgesics to be tolerable. Moreover, the application of excessive pressure can at times totally occlude the underlying blood vessel, resulting in ischemia and/or thrombosis.
Following manual compression, the patient is required to remain recumbent for at least four, and at times as long as eighteen, hours under close observation to assure continued hemostasis. During this time, renewed bleeding may occur resulting in bleeding through the tract, hematoma and/or pseudoaneurysm formation as well as arteriovenous fistula formation. These complications may require blood transfusion and/or surgical intervention. The incidence of these complications increases when the sheath size is increased.
The post-procedure hemostasis problem is further aggravated by the use of anticoagulant drug therapy. Such drug therapy is almost always indicated for patients requiring catheter laboratory procedures. Anticoagulants help prevent complications such as coronary artery clots which could cause a heart attack but at the same time, make achieving hemostasis very difficult using conventional methods. Typically, although it is undesirable, anticoagulants are discontinued for several hours so that hemostasis can be achieved. It would be particularly beneficial to achieve hemostasis without the risks associated with discontinuing anticoagulant therapy.
It is clear that the standard technique for arterial closure can be risky, uncomfortable to the patient and expensive due to the need for post procedure observation costs. While the risk of such conditions can be reduced by using highly trained individuals, such use is both expensive and inefficient. If the closure fails and bleeding occurs, the site must be compressed again or vascular surgery is required.
To overcome the problems associated with manual compression, several groups have proposed the use of bioabsorbable fasteners to stop bleeding. A thrombogenic and bioabsorbable material, such as collagen, is placed at the superficial arterial wall over the puncture site. While potentially effective, this approach suffers from a number of problems. It can be difficult to properly locate the interface of the overlying tissue and the adventitial surface of the blood vessel. Furthermore, locating the fastener in the incorrect location can result in failure to provide hemostasis and subsequent hematoma and/or pseudoaneurysm formation. Conversely, if the fastener intrudes into the arterial lumen, intravascular clots and/or collagen pieces with thrombus attached can form and embolize downstream causing vascular occlusion. Also thrombus formation on the surface of a fastener protruding into the lumen can cause a stenosis which can obstruct normal blood flow. Other possible complications include infection as well as adverse reactions to the implant.
One alternative to manual compression and bioabsorbable fasteners is suturing the access site. However, vascular structures are logistically difficult to suture because of their structure and location deep within the body. One device, described in U.S. Pat. No. 5,417,699, includes a shaft for introducing a pair of needles inwardly through the puncture site and then drawing the needles outwardly back through the tissue on either side of the puncture site. The needles are bent so that the pointed ends of the needles can be captured by the device after they have passed through the tissue. The shaft can then be withdrawn to carry the needles and attached suture outwardly back through the tract.
Although this device provides means for immediate closure of a vascular wound, it can damage the vascular structure by increasing the size of the wound to accommodate the device or by tearing the surrounding tissue. Also, because the device delivers each suture simultaneously, the device must be perfectly aligned within the wound. Furthermore, it is not possible to selectively deliver a stitch or to vary the suture pattern. Moreover, the device requires special bendable needles so that the needles can be captured after delivering a suture. The complicated design of the device is fragile and cumbersome and increases the risk of operator failure and device malfunction.
A need has remained for devices and methods which safely and efficiently effect homeostasis after vascular procedures. In particular, a need exists for suturing assemblies which provide means for convenient and efficient suturing of vascular wounds. A need also exists for suturing guides which utilize conventional needles and suture material. A further need has remained for suturing guides which provide flexible suturing patterns.